Fairy king (6)
I believe the answer is:
oberon
'fairy king' is the definition.
(Oberon is a mythical fairy king)
This is the entire clue.
(Other definitions for oberon that I've seen before include "charming king" , "MND fairy king" , "...[IN DREAM] with king" , "Titania's husband" , "Fairy king (AMND)" .)